Local Color

 

Prof. Valeri Krongauz is not content with seeing life only through rose-tinted glasses. His research has made it possible to manufacture self-tinting eyeglasses that, upon exposure to the sun, darken and assume any color of the spectrum, from yellow to red to blue.

 

Krongauz, a professor emeritus in the Weizmann Institute’s Organic Chemistry Department, is one of the world’s leading experts on organic photochromic materials – carbon-based substances that change color when exposed to bright light. One of his inventions has led to the establishment of Chromtech Ltd., a company in the Rabin Science Park adjacent to the Institute that sells photochromic materials to manufacturers of self-tinting eyeglasses.

 

Due to the complexity and the costs involved in making self-tinting plastic lenses, only a handful of large companies worldwide possess the necessary technology. Other lens manufacturers – along with manufacturers of self-tinting films for car windows – can now purchase self-tinting material from Chromtech in powder form.

 

A major advantage of Chromtech’s photochromic materials is that, thanks to their intense tinting ability, they can be either dissolved within the plastic lens or used as a component of a thin coating. The coating, which is stable and highly sensitive, can be easily applied to the surface of any plastic lens. Its darkening results from a relatively minor molecular event: A photochromic structure changes its color when it absorbs a photon of light, which breaks just one of its chemical bonds; once the light disappears, the bond bounces back into place and the structure returns to its original color.

 

Organic photochromic materials were discovered at the Weizmann Institute in 1952. At the height of the Cold War, the substances attracted the attention of Soviet scientists, who sought to use them for making protective goggles against the blinding radiation emitted after the explosion of an atomic bomb. Krongauz, who worked at the time in a large physical chemistry institute in Moscow, stayed clear of the military research because, like many other Soviet Jews, he was concerned that knowledge of military secrets might later prevent him from leaving the country. Besides, he was drawn to basic research, and he focused on fundamental studies of photochromic materials, which, apart from posing interesting scientific questions, attracted him by their aesthetic beauty.

 

After immigrating to Israel and joining the Weizmann Institute in 1976, he made groundbreaking contributions to the theory of photochromism and other areas of organic chemistry, and conducted pioneering research in an area today known as nanoscience. One of his applied projects led to the establishment of Chromtech, which Krongauz, now its chief technology officer, founded in 1999 together with Amram Masad, the company’s president and CEO, under a license from Weizmann’s Yeda Research and Development Co. Ltd.

 

Chromtech today employs half a dozen chemists, all from Russia and all holding Ph.D. degrees. One of the company’s potential future projects is to develop self-tinting intraocular lenses, the implants inserted during eye surgery when the eye’s natural lens is clouded by a cataract. Another promising development is the plasma technology for applying a very thin layer of the self-tinting material as a vapor under vacuum conditions. Chromtech’s sales have been growing steadily over the past few years and seem likely to continue to grow – a good reason for optimism, even without wearing rose-tinted glasses.